The spoken word can now be recognized by computer and is the most intuitive text input method, however input of spatial data has always been subject to a poor compromise. Generally a 2D device such as a mouse is used; but it is both inadequate for 3D space and does not feedback any physical presence of objects. To the pointer the workspace is only an image.
Achieving more intuitive spatial input would enable increased design and manipulation productivity and not surprisingly has been the goal of many researchers. The class of device under consideration is known as haptic. In its perfect form, it is a type of input device that allows the user to ‘feel’ virtual objects as if he was touching a real model.
Currently available examples range from joysticks with some force feedback to articulating exoskeletons permitting interaction with the virtual workspace or even telerobotic control of distant robots.
There are several low cost and highly practical six axis force sensing input devices available. They are employed by CAD operators to orientate a virtual model within the workspace. But without any significant control stick displacement they are relative move only—you cannot use them to quickly find a position, you have to steer yourself there with force vector adjustments. However they are effective at selecting a model viewing position (which does not require high resolution) and being relative move permit ranging over an unlimited workspace.
Recently haptic (force feedback) devices have become available that enable absolute six axis position measurement within their working volume—which is then scaled to the size of the desired virtual workspace. Absolute position input is the most intuitive method as it maps direly to the position of the hand. The disadvantage is the finite work volume. If a CAD user needs to work in detail on a big model, it is necessary to repeatedly reset the origin or scale of the workspace, which is cumbersome.
In an ideal world the user would be able to range seamlessly between large relative displacements and fine detail absolute control.
Haptic devices generally include six axis force sensing as part of their system. They use it to sense movement intent and then enable the motion; either as freely as possible or with programmed resistance. Force feedback also enables attractive software features such as modeling compliant solids (virtual clay) and deforming complex curvature surfaces.
Special haptic devices for finger movement rather than hand movement have been developed, sometimes linked into an entire haptic exoskeleton. The trouble is that these systems are complex and costly. They also generally require that the user's body be strapped into the device. There remains a need for a more practical and cost effective solution.
Given due regard to practicality, a desirable embodiment would be a desktop pointer that can be moved about all six degrees of freedom but with it's motion limits mechanically constrained under computer control to prevent encroachment into the body of a virtual model; perhaps with a handle that can be treated like a stylus. To varying degrees this can now be technically achieved—but at a high cost, which severely limits it's adoption.